Apparatus for injecting fluids into well bores



R. H. CARR ETAL Sept. 23, 1952 APPARATUS FOR INJECTING' FLUIDSVINTO WELL BORES Filed April 26, 1948" 2 SI-IEETS-SAEET 1 fil l l l HU l II I l JNVENTORS. 19/67/11:?0 A! 6141?? Kill/#57774. CQl zl 'kml f,

Fla.

ATTORNEY v Patented Sept. 23, 1952 UNITED, STATE APPARATUS FOR INJE CTING FLUIDS INTO WELL'BORES I 7 Richard H. Carr, Chicago,

and Kenneth A. Covell,

Winnetka, 111., assignorst'o The Pure Oil Com; pany, Chicago, 111., a corporation of Ohio Application April26,1 948.Seria1No;23,338

' (cr es-'1 to be forced into the formation, of low permeability, Mechanical packers and chemical sealing agents have been used to accomplish the selective sealing which is necessary to make possible the selective flooding. In accordance with ourinvention, we use a collapsible or inflatable packer controlled by a mechanism which regulates the relative pressures within and without the packer to provide for sealing off the formations of high permeability. to avoid application of a bursting pressure to thesealer, and to permit-the fluid to be injected into the formations of low permeability.

One of the objects of our invention is to provide a method forselectively repressuring our flooding subterranean oil formations. I

Another object of the invention is to provide apparatus for selective sealing of different forma tions along an earthbore.

Still another objector theinvention is to provide a diflerential pressure typeexpansible and collapsible packer for use in-earth bores. H

further object of the invention is to provide apparatus for control of the differential pressure on a collapsible and expansible packer in an earth bore.

Still another object ofthe invention is to provide a method and apparatus for controlling the volume and pressure of fluid injected into a well bore.

A still fur her object of the invention is to provide method and apparatus which will permit acidizing and sealing ofselectedstrata along'a en e. 1 pther objects of the invention will part be obvious and in part appear hereinafter.-

The invention, accordingly, includes an appaexisting in the interior thereof and that in the surrounding space in the bore to cause fluid to permeate the strata it is desired to flood and to lgeep pressure; inthe bag within its burstin strength. The invention also includes the methed; by which the flowof fluid into the-stratais controlled by having its pressure andthe resistance in its path of flow matched to thepermeability differences-occurring along the well bore.

In the usual operation where fluid injection into sections of well bores is employed as a means forsecondary recovery, it is common experience thatl the most permeable strata occurring in the ratus for use in the bore hole of a well with which selected strata occurring alongthelength of the well can be sealed off, the apparatus including a bag made of flexible materials having, degrees of permeability matched to the permeabilities of the several earth strata in the well adjacent to the bag positioned therein, and a mechanism for use with the bag, subject to operation by the fluid being injected into the well, so that an optimum pressure differential is maintained between that formations through which the bore passes will take up most of the injected fluid, with the result that the effective driving force thereof is largely confined to flushing these sections, leaving the less permeable strata unaffected or only partially.affected.- In viewv of the fact that it is the less permeable strata which retainthe greater amount of oil, it isof prime importance to accomplish "a thorough flushing thereof in the secondary recove'ry"operation. By use ofthe ap paratus constituting this invention according to the method to be describedfselective and substantially quantitative control of the flow of fluids into various sections of the bore holes of wells can be achieved. l It is possible that it might be desirable to avoid forcing the fluid into'a given stratum'in a well. In such a case, an impermeable bag or section would be placed opposite that stratum. In practice, a rubber'b'ag has been found suitable.

'Figure 1 isa diagrammatic longitudinal section on a reduced scale of anoil well bore indicating in. a conventional form the. location and nature of several'j-typi'calstrataof different porosities and showinga bag made for selectivesealing set inv p'lace'in accordance with our invenon; Figure 2 "is a longitudinal [sectional view through a difierential pressure releasing valve which is usedin conjunction with the apparatus to develop thedesired'control-over the fluid flow; 1 Figure 3'is'a lonigitudinal section of a well bore showing a selective sealing arrangement embodying an alternativeform of our invention; Figure 4 is 'a longitudinal section through an alternative form'of di'fierentialfpressure release valve;

Figure 5 shows, aplot giving a profile of a typi cal well bore in terms of permeability of thevsever'al strata encountered. V

In Figure 1, 10 represents a, well borepassing irom thesurface'of theearth [1 through non- For the purpose of selectively flooding the several less permeable strata during the repressuring operations, the bag 2| is made in sections of different permeabilities, 23, 24, 25, 25, 27 and 28,- to match the permeabilities of the several sec-f tions occurring in the formation through which Thus, at those formations of high permeability, for example those indicated the well bore passes.

as 3, 5 and I"! in the diagram, the bag consists of a material of tight, substantially fluidimpervious weave. Opposite sections of low permeability, for example, those indicated as M, It and 8 in the diagram, sections of the bag are of loose-weave material and corresponding high permeability. The bottom of the bag is drawn down close to the bottom of the well by the-inclusion of 'aweight 29 in a compartment forming its termination.

Figure 2 shows a sectional view of a pressure diiferential release valve which is the connecting link between the bag 2| and the end of tubing 20. The valve comprises what is essentially a bushing-30 having a threaded section 3| for engaging the: tubing 20, and a section 32 of reduced diameter for connection with the bag 2|. Channels 3'3, 34 35, in the bushing are arranged to provide communication from inside the bag 2| to the outside. The several channels 33, 34, 3-5, enlarge into housings 36, 31, 38, which enclose sealing balls 3 9'loaded with spring 39', 4O loaded with spring 40', and 4| loaded with spring 4|. These balls coactingwith thesprings and channels function as check valves so that when a, critical pressure differential between the inside and outside develops, they permit unidirectional flow of liquid through the differential release valve to the outside.

In Figure 3 there is shown a second arrangement of elements in which closely; woven .sections ofmaterial, 50, 5|, and 52, are" alternated with sections of: perforated tubing 53, 54', 55, which are'open toflowof fluid to an extent such that they replace the loose weave material; described inconjunction with Figure 1.

Figure 4 shows a longitudinal cross section. of an alternative form of differential pressure valve for the maintenance of an equilibrium difljerential' pressure between the inside andthe outside of a flexible bag inserted in the well. In the figure, 60 represents an end of the well tubing ;to which there is attached a bushing 6|. carrying a metal skirt -6 2 which enlarges toa diameter somewhat greater than. the outside diameter of the tube extension;63,, so, that the. skirt and the tube 63 define an annular space 64', Thepurpose of theskirtisto provide a protecting canopy over spring loaded orifice covers 65;.and165, the only; two shownin the'flgure. The orifice covers are made up of spring steel levers 67, 68, carrying gasket buttons 69 and It on the respective ends thereof to cover the orifices 1| and 2; The dimensions of the spring levers 61 and- 68 are matched to the orifices and "to yield at a certain internal pressure, whereupon the-buttons areforced away fromthe orifices to allow fluid to flow out. When an equilibrium differential between the interior and the exterior pressures is attained, the springs will have suflicient resilience to force the buttons back into place. In this manner, the valve will maintain an equilibrium differential pressure between the interior and exterior of the packer unit. I

For the most successful-practice of our invention, it is desirable to have a fairly complete log of a well bore showing its profile and comparative oil saturation percentages in the several strata encountered so that selective sealing can be judiciously applied to develop maximum rates of flow from the strata it is desired to strip. Such a. diagram is found in Figure 5 which shows for a typical well, percentages of oil saturation logged. against depth, and a quantitative measure of the porosity of the sections throughout the well.

Having once obtained a reasonably accurate log of thewell, it becomes necessary then to'construct a bag-which will have awea-ve of varying tightness along its length so' that its permeability along its length is the inverse of the permeabilities encountered in the well. That-is to say, the sections of the bag having the lowest permeabilities will be placed to fall opposite those sections of the well having'the highest permeabilitiesdn order to control the flow of fluid thereinto. Natural limitations onthe injection of fluid into the well make most convenient the application of one pressure to all ofthe several sections of thewell being flooded. By inserting the bag having sections ofdifferent permeabilities into the well, the changes in resistance to fluid flow into the well strata are such that a relatively smooth flowof fluid is developed.

Where no log of the well is available, the repressuring and selective sealing can be'done empirically by successively blocking various strata in the bore and continuingto seal those at which a pressure-is developed;

To applythe apparatus'in a selective sealing and flooding operation, the bag, for example as shown in Figure 1, is connected totube-'20 by means of diiferential release valve30 which provides for communication between the interiorof the bag and exterior ofthetube, which is the annularspace between the well casing and tub'e. When fluid-isinjected through tube-'20fit fills the bag and causes it to expand andpress against the sides of-the well bore. The differentpermeabilities of "the-several sections of the bag will alter the resistance to fluid flow at the several strata with the resultthat different amounts of fluid will flow into the several sections through the well. While the flow of fluidis out through the bag and into the permeable strata, balls 39 and 40 in differential; pressure valve 30 willbe raised to permit flow "intothe annular space. When the flow has continueduntil a head? of liquid or fluid pressure is built up in thean'nular space betweentubing and-' casing 'the' pressure difference on the two sides of the valve will-reach a point such; that the springloadedballs- 39and 40 will be-forced back to their positions and flow offluid from the tube through the-valves will cease.-- The net effect isthat liquid; in the tube and annulus will coact-to force liquid into the strata; thefirst applying a pressure tothe interior of the-bag, the second applying apressure to the exteriorthereof, with the result that thepossibility of burstingthe bag'iseliminated':

In this manner, it'is' found that aniautotnatic development of the predetermined pressure'difentstr a n h d whi n be, 91-

erated th m e ifiere lrr ss re ea e; va v op a .whahme; the 5 Y mama-mirea ro P e ser niie ;..be-

we n e herth h a d. that 9 the tap I te bo tom ti a. e se 9i bur efihabe b h fii p p 39 .11 .5 11? pr re i thminated.

The manner in which the diflerential valve shown in Figure 4 operates is substantially the same as that shown in Figure 2. Spring levers 61 and 68 operate the balance one pressure against the other.

The operation of the embodiment of the packer described in Figure 3 is fairly evident from the appearance of the drawing. Perforated lengths of tubing found between the sections of the tightly woven bag correspond to the loosely woven material of the bag described in connection with Figure l. The remainder of the operation of the device corresponds precisely with that of the valve described in connection with Figures 1 and 2.

When it is desired to discontinue a flooding operation and remove the bag, it can be done simply by reversing the pressure differential on the bag. That is, by forcing fluid into the annulus, the pressure there is elevated and the bag collapsed.

Other variations of this flexible bag method of adjusting the permeability of subterranean strata to injection fluids include slipping the bag assembly into the well onto devices set in the formation or set in the casing and permitting the bag element to extend down into the hole to points opposite the wall of the bore hole where selected sections may be treated as indicated in the foregoing figures. Not only can the selective adjustment of the permeability of the earth 4 strata be used for flooding the strata, but it can also be used for sealing, aci-dizing, or feeding plastic plugging and cementing materials into sections of wells where it is desired to have these materials come to a point opposite selected portions of the bore hole. When wells are acid treated, it is often the case that a given well is producing from more than one stratum in the bore hole, and in the conventional acid treatment, the lowermost permeable section will usually get all the benefit of the acid. As indicated here, means can be employed to direct the injection of acid into these strata which it is desired to treat and, thus, improve the efliciency of the treatment in reaching all of the sections which would be treated.

The particular qualities of the material to be used for the adjustment of the permeability are, naturally, that it should be of a material unaffected by crude oil or by the fluid it is desired to inject into the well. Various materials can be used, among which is glass fiber cloth, which material in addition to having a very high tensile strength, can be made in various degrees of permeability-so that the proper adjustment of the resistance can be readily made. For further adjustment of the permeability of the material to be used, it can be coated or impregnated with various plastic paints, resins, such as the polyvinyl chlorides, asphalt and rubber base paints,

6 or phe'nol formaldehyde resins and .othensealing materials? which: make? the materia 21 .l'leed very resistant or substantially impenvinpsto r n9 yeg 1 nt of fluid through its weave. Where an imper meable bag or section desired, it can be made :m ..-.i-J-..

Though this" apparatus and method for flooding wells has been described with a restricted number of examples, they should be taken as 11-- lustrative'and not in a limiting sense.

Whatisclaimedis:

1. An apparatus for adjusting the resistance to fluid flow of the walls of an earth bore passing through a plurality ofsubterranean earth strata of dififerent permeabilities which comprises a multi-sectioned, fluid pervious, flexible envelope inflatable to a shape substantially matching the diameter of the bore and length of strata to be treated, the respective sections of said envelope being of varying permeability along its length, said permeabilities being inversely related to the permeability of the stratum contiguous to each section and the length of each section being substantially coextensive with the length of the respective stratum contiguous thereto, said permeable sections being prepared from naturally pervious, woven fabrics, a means attached adjacent to the terminal extremity of said envelope for affixing a weight thereto, a conduit communicating with the interior of said envelope for introducing fluid thereinto, and a means communicating with the interior and exterior of the envelope to provide for the maintenance of a predetermined pressure differential between the interior and exterior of said envelope sufiicientto seat said envelope against the walls of the earth bore, said means being adapted to provide unidirectional fluid flow from within the said envelope.

2. An apparatus in accordance with claim 1 in which the envelope has a diameter and length slightly greater than the diameter and length of the earth bore so that upon inflation of said envelope to a predetermined pressure the outer wall of said envelope will seat itself with the walls of said earth bore in contiguous relationship thereto substantially throughout the length of said envelope.

3. An apparatus for adjusting the resistance to fluid flow of the walls of an earth bore passing through a plurality of subterranean earth strata of different permeabilities which comprises a multisectional packer, the sections of which are fluid pervious, flexible and inflatable to a shape substantially matching the diameter of the bore and length of strata to be treated, the respective sections of said packer being of diflerent permeabilities, said permeabilities being inversely related to the permeability of the stratum contiguous to each section and the length of each section being substantially coextensive with the length of the respective stratum contiguous thereto, said permeable sections being prepared from naturally pervious, woven fabrics, a means attached adjacent to the terminal extremity of said packer for afiixing a weight thereto, a conduit communicating with the interior of said sections for introducing fluid thereinto, and a means communicating with the interior and exterior of the sections to provide for the maintenance of a predetermined pressure differential between the interior and exterior thereof sufiicient to seat said sections against the wall of the earth bore, said means being adapted to provide unidirectional fluid flow from within the said sections. 

